Rav Yitzchok Adlerstein wrote:
There are people who believe that shaking hands with those of the opposite gender is not only assur, but yehareg v’al ya’avor. Teachers should not be muzzled into not relating this. At the same time, with what we know of what is going on in the minds of so many of our teens (and their parents!), a good teacher ought to be able to relate the difference between committing adultery and abizrayu of ervah. He/she ought to also explain that such a position is hardly unanimous: that frum, pious German Jews shook hands for hundreds of years; that some major figures in the previous generation held that it was mutar, at least in trying circumstances; that R. Chaim Berlin wrote a teshuvah explaining why it is mutar. The teacher ought to be able to adequately explain the position that he/she does not practice, even while promoting the other.